Tribological properties of diamond films

ABSTRACT

Methods to manufacture integrated circuits are described. Nanocrystalline diamond is used as a hard mask in place of amorphous carbon. Provided is a method of processing a substrate in which nanocrystalline diamond is used as a hard mask, wherein processing methods result in a smooth surface. The method involves two processing parts. Two separate nanocrystalline diamond recipes are combined—the first and second recipes are cycled to achieve a nanocrystalline diamond hard mask having high hardness, high modulus, and a smooth surface. In other embodiments, the first recipe is followed by an inert gas plasma smoothening process and then the first recipe is cycled to achieve a high hardness, a high modulus, and a smooth surface.

TECHNICAL FIELD

Embodiments of the present disclosure pertain to the field of electronicdevice manufacturing, and in particular, to an integrated circuit (IC)manufacturing. More particularly, embodiments of the disclosure providemethods of depositing nanocrystalline diamond films.

BACKGROUND

As the semiconductor industry introduces new generations of integratedcircuits (ICs) having higher performance and greater functionality, thedensity of the elements that form those ICs is increased, while thedimensions, size, and spacing between the individual components orelements are reduced. While in the past such reductions were limitedonly by the ability to define the structures using photo lithography,device geometries having dimensions measured in μm or nm have creatednew limiting factors, such as the conductivity of the metallic elements,the dielectric constant of the insulating material(s) used between theelements, or challenges in 3D NAND or DRAM processes. These limitationsmay benefit by more durable and higher hardness hard masks.

The direct way to reduce cost per bit and increase chip density in 3DNAND is by adding more layers. One of the critical steps in 3D NANDtechnology is slit etch prior to silicon nitride (SiN) recess for metalcontact deposition. As the number of tiers increase in each technologynode, to control the slit etch profile (uniform etching from top tobottom), the thickness of the hard mask has to be proportionallyincreased to withstand high aspect etch profiles. Traditionally, a veryhigh-quality hard mask film, which has high etch selectivity,unparalleled hardness, and high density is used. Current hard mask filmsinclude pure or doped plasma enhanced chemical vapor deposition (PECVD)amorphous carbon (aC:H) based films due to high hardness and modulus,film transparency, and ease in removing after slit etching. PECVDamorphous carbon hard mask films, however, have problems withdelamination/peeling at bevel (major issue in downstream etch process),becoming more opaque with thicker films (photo alignment issue), andpoor morphology, leading to pillar striations, one sided bow, and pillartwisting.

Nanocrystalline diamond is known as a high hardness material which canbe used as a hard mask in semiconductor device processing.Nanocrystalline diamond hard mask films, while having high hardness andmodulus, have high surface roughness. Accordingly, there is a need forhard masks that have high hardness and modulus, but that have lowsurface roughness.

SUMMARY

Apparatuses and methods to manufacture integrated circuits aredescribed. In one or more embodiments, a processing method is described.In one embodiment, a processing method comprises: depositing a firstnanocrystalline diamond layer on a substrate, the first nanocrystallinediamond layer having a first thickness, a first roughness, a firsthardness, and a first modulus; and depositing a second nanocrystallinediamond layer on the first nanocrystalline diamond layer, the secondnanocrystalline diamond layer having a second thickness, and a secondroughness, wherein the first thickness is greater than the secondthickness, and the second roughness is less than the first roughness.

In other embodiments, a processing method comprises depositing a firstnanocrystalline diamond layer on the seed layer, the firstnanocrystalline diamond layer having a first thickness, a firstroughness, a first hardness, and a first modulus; and exposing the firstnanocrystalline diamond layer to an inert gas plasma to form a smoothnanocrystalline diamond layer.

In one or more embodiments, an electronic device is described. Thememory device comprises: a memory stack comprising a plurality ofalternating layers of a first material and a second material on asubstrate; a nanocrystalline diamond layer on the memory stack, thenanocrystalline diamond layer has a roughness of less than about 15 nm;and a memory channel extending from a top surface of the memory stack tothe substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments. The embodiments as described herein areillustrated by way of example and not limitation in the figures of theaccompanying drawings in which like references indicate similarelements.

FIG. 1A illustrates a cross-sectional view of a substrate according toone or more embodiments;

FIG. 1B illustrates a cross-sectional view of a substrate according toone or more embodiments;

FIG. 1C illustrates a cross-sectional view of a substrate according toone or more embodiments;

FIG. 1D illustrates a cross-sectional view of a substrate according toone or more embodiments;

FIG. 2A illustrates a cross-sectional view of a substrate according toone or more embodiments;

FIG. 2B illustrates a cross-sectional view of a substrate according toone or more embodiments;

FIG. 2C illustrates a cross-sectional view of a substrate according toone or more embodiments;

FIG. 2D illustrates a cross-sectional view of a substrate according toone or more embodiments;

FIG. 3A illustrates a cross-sectional view of a substrate according toone or more embodiments;

FIG. 3B illustrates a cross-sectional view of a substrate according toone or more embodiments;

FIG. 3C illustrates a cross-sectional view of a substrate according toone or more embodiments;

FIG. 4A illustrates a cross-sectional view of a substrate according toone or more embodiments;

FIG. 4B illustrates a cross-sectional view of a substrate according toone or more embodiments;

FIG. 4C illustrates a cross-sectional view of a substrate according toone or more embodiments;

FIG. 4D illustrates a cross-sectional view of a substrate according toone or more embodiments;

FIG. 5 illustrates a flow diagram of a method according to one or moreembodiments; and

FIG. 6 illustrates a flow diagram of a method according to one or moreembodiments.

DETAILED DESCRIPTION

Before describing several exemplary embodiments of the disclosure, it isto be understood that the disclosure is not limited to the details ofconstruction or process steps set forth in the following description.The disclosure is capable of other embodiments and of being practiced orbeing carried out in various ways.

A “substrate” as used herein, refers to any substrate or materialsurface formed on a substrate upon which film processing is performedduring a fabrication process. For example, a substrate surface on whichprocessing can be performed include materials such as silicon, siliconoxide, strained silicon, silicon on insulator (SOI), carbon dopedsilicon oxides, amorphous silicon, doped silicon, germanium, galliumarsenide, gallium nitride, glass, sapphire, and any other materials suchas metals, metal nitrides, metal alloys, and other conductive materials,depending on the application. Substrates include, without limitation,semiconductor wafers. Substrates may be exposed to a pretreatmentprocess to polish, etch, reduce, oxidize, hydroxylate, anneal and/orbake the substrate surface. In addition to film processing directly onthe surface of the substrate itself, in the present disclosure, any ofthe film processing steps disclosed may also be performed on anunder-layer formed on the substrate as disclosed in more detail below,and the term “substrate surface” is intended to include such under-layeras the context indicates. Thus for example, where a film/layer orpartial film/layer has been deposited onto a substrate surface, theexposed surface of the newly deposited film/layer becomes the substratesurface.

As used in this specification and the appended claims, the terms“precursor”, “reactant”, “reactive gas” and the like are usedinterchangeably to refer to any gaseous species that can react with thesubstrate surface.

As used herein, the phrase “nanocrystalline diamond,” refers a solidfilm of diamond typically grown on a substrate, such as silicon. Thenanocrystallinity is the results of the enhanced re-nucleation reactionin diamond growth, where the growth of diamond crystal is disrupted dueto the fluctuation of surrounding environments such as the amounts ofradical species, temperature and pressure. The formation of diamondnuclei is determined by the hydrogen atoms which play an important rolein driving external carbon atom adsorption and etching away thenon-diamond phases, and it is believed to be the competition betweendiamond growth and etching. Nanocrystalline diamond are mainly comprisedof small diamond crystal in nanospheres or nanocolumnar shape, and theamorphous carbon distributed usually distribute in the positions betweensurrounding crystals or accumulate in the grain boundaries.Nanocrystalline diamond is used as a hard mask material in semiconductorapplications because of its chemical inertness, optical transparency,and good mechanical properties.

In one or more embodiments, plasma enhanced chemical vapor deposition(PECVD) is widely used to deposit nanocrystalline diamond films due tocost efficiency and film property versatility. In a PECVD process, ahydrocarbon source, such as a gas-phase hydrocarbon or vapors of aliquid-phase hydrocarbon that have been entrained in a carrier gas, isintroduced into a PECVD chamber. Plasma is then initiated in the chamberto create excited CH-radicals. The excited CH-radicals are chemicallybound to the surface of a substrate positioned in the chamber, formingthe desired nanocrystalline diamond films thereon. Embodiments describedherein in reference to a PECVD process can be carried out using anysuitable thin film deposition system. Examples of suitable systemsinclude the CENTURA® systems which may use a DXZ® processing chamber,PRECISION 5000® systems, PRODUCER® systems, PRODUCER® GTTM systems,PRODUCER® XP Precision™ systems, PRODUCER® SETM systems, Sym3®processing chamber, and Mesa™ processing chamber, all of which arecommercially available from Applied Materials, Inc., of Santa Clara,Calif. Other tools capable of performing PECVD processes may also beadapted to benefit from the embodiments described herein. In addition,any system enabling the PECVD processes described herein can be used toadvantage. Any apparatus description described herein is illustrativeand should not be construed or interpreted as limiting the scope of theimplementations described herein.

Device manufacturers using a carbon-based hard mask layer demandcritical requirements be met: (1) high selectivity of the hard maskduring the dry etching of underlying materials, (2) low film roughness,(3) low film stress, and (4) film strip ability. As used herein, theterm “dry etching” generally refers to etching processes where amaterial is not dissolved by immersion in a chemical solution andincludes methods such as plasma etching, reactive ion etching, sputteretching, and vapor phase etching.

In one or more embodiments, a nanocrystalline diamond layer is formed ona substrate. The process of one or more embodiments advantageouslyproduces a nanocrystalline diamond layer with high density, highhardness, high etch selectivity, low stress and excellent thermalconductivity.

Hard masks are used as etch stop layers in semiconductor processing.Ashable hard masks have a chemical composition that allows them to beremoved by a technique referred to as ashing once they have served theirpurpose. An ashable hard mask is generally composed of carbon andhydrogen with trace amounts of one or more dopants (e.g., nitrogen,fluorine, boron, silicon). In a typical application, after etching, thehard mask has served its purpose and is removed from the underlyinglayer. This is generally accomplished, at least in part, by ashing, alsoreferred to as “plasma ashing” or “dry stripping.” Substrates with hardmasks to be ashed, generally partially fabricated semiconductor wafers,are placed into a chamber under vacuum, and oxygen is introduced andsubjected to radio frequency power, which creates oxygen radicals(plasma). The radicals react with the hard mask to oxidize it to water,carbon monoxide, and carbon dioxide. In some instances, complete removalof the hard mask may be accomplished by following the ashing withadditional wet or dry etching processes, for example when the ashablehard mask leaves behind any residue that cannot be removed by ashingalone.

Hard mask layers are often used in narrow and/or deep contact etchapplications, where photoresist may not be thick enough to mask theunderlying layer. This is especially applicable as the criticaldimension shrinks.

V-NAND, or 3D-NAND, structures are used in flash memory applications.V-NAND devices are vertically stacked NAND structures with a largenumber of cells arranged in blocks. As used herein, the term “3D NAND”refers to a type of electronic (solid-state) non-volatile computerstorage memory in which the memory cells are stacked in multiple layers.3D NAND memory generally includes a plurality of memory cells thatinclude floating-gate transistors. Traditionally, 3D NAND memory cellsinclude a plurality of NAND memory structures arranged in threedimensions around a bit line.

A critical step in 3D NAND technology is slit etch. As the number oftiers increases in each technology node, to control the slit etchprofile, the thickness of the hard mask film has to proportionallyincrease to withstand high aspect etch profiles. Currently, amorphouscarbon (aC:H) films are used due to high hardness and easy to stripafter slit etch. However, amorphous carbon hard mask films havedelamination at bevel and poor morphology, leading to pillar striations.

Tribology is the science and engineering of interacting surfaces inrelative motion. Tribology includes the study and application of theprinciples of friction, lubrication, and wear. In one or moreembodiments, nanocrystalline diamond is advantageously used as a hardmask in place of amorphous carbon. Nanocrystalline diamond hard maskfilms provide high hardness and high modulus, but can result in highlevels of surface roughness. Accordingly, in one or more embodiments,provided is a method of processing a substrate in which nanocrystallinediamond is used as a hard mask, wherein processing methods result in asmooth surface. The method of one or more embodiments involves twoprocessing parts. In one embodiment, two separate nanocrystallinediamond recipes are combined—the first recipe provides high hardness andhigh modulus and the second recipe provides a smooth surface. The firstand second recipes are cycled to achieve a nanocrystalline diamond hardmask having high hardness, high modulus, and a smooth surface. In otherembodiments, the first recipe is followed by an inert gas plasmasmoothening process and then the first recipe is cycled to achieve ahigh hardness, a high modulus, and a smooth surface.

The processing methods of one or more embodiments advantageouslypreserve the nanocrystalline diamond hard mask film's hardness andmodulus while keeping the surface roughness low. With thenanocrystalline diamond hard mask film's high hardness, high modulus andimproved surface roughness, the film can be used as a hard mask toovercome the challenges faced in the amorphous carbon-based films.

In one or more embodiments, to achieve greater etch selectivity, thedensity and, more importantly, the Young's modulus of thenanocrystalline diamond layer 108, 208 is improved. One of the mainchallenges in achieving greater etch selectivity and improved Young'smodulus is the high compressive stress of such a film making itunsuitable for applications owing to the resultant high wafer bow.Hence, there is a need for nanocrystalline diamond films withhigh-density and modulus (e.g., higher sp³ content) with high etchselectivity along with low stress (e.g., <−500 MPa).

Embodiments described herein, include improved methods of fabricatingnanocrystalline diamond hard mask films with high-density (e.g., >1.8g/cc), high Young's elastic modulus (e.g., >150 GPa), and low stress(e.g., <−500 MPa). In one or more embodiments, the Young's modulus ismeasured at room temperature, or at ambient temperature, or at atemperature in the range of from about 22° C. to about 25° C. In one ormore embodiments, Young's modulus of the nanocrystalline diamond filmmay be greater than 250 GPa. In other embodiments, Young's modulus ofthe nanocrystalline diamond film may be greater than 300 GPa, or greaterthan 350 GPa.

In one or more embodiment, the density of the nanocrystalline diamondfilm is greater than about 3.0 g/cc.

FIGS. 1A-1D illustrate schematic cross-sectional views of a substrate100 at different stages of an integrated circuit fabrication sequence,the first recipe, incorporating a nanocrystalline diamond layer as ahard mask. In FIGS. 1A-1D, the nanocrystalline diamond layer 108 that isdeposited has a thickness, T₁, a high modulus (E>250 GPa) and a highsurface roughness (Ra>25 nm). In one or more embodiments, the firstnanocrystalline diamond layer 108 has a thickness, T₁, in a range offrom about 250 nm to about 650 nm. In one or more embodiments, theroughness of the nanocrystalline diamond layer 108, as measured byatomic force microscopy (AFM), is greater than 25 nm.

FIGS. 2A-2D illustrate schematic cross-sectional views of a substrate200 at different stages of an integrated circuit fabrication sequence,the second recipe, incorporating a nanocrystalline diamond layer as ahard mask. In FIGS. 2A-2D, the nanocrystalline diamond layer 208 that isdeposited has a thickness, T₂, a high modulus (E>250 GPa) and a lowsurface roughness (Ra<15 nm). In one or more embodiments, the secondnanocrystalline diamond layer 208 has a thickness, T₂, in a range offrom about 5 nm to about 200 nm. In one or more embodiments, theroughness of the nanocrystalline diamond layer 208, as measured byatomic force microscopy (AFM), is less than about 15 nm.

FIG. 1A illustrates a cross-sectional view of a device 100. In one ormore embodiments, the device 100 may be a NAND device. The device 100includes a substrate 102, a plurality of device layers 104, 106, ananocrystalline diamond mask layer 108 formed on the plurality of devicelayers 104, 106.

FIG. 2A illustrates a cross-sectional view of a device 200. In one ormore embodiments, the device 200 may be a NAND device. The device 200includes a substrate 202, a plurality of device layers 204, 206, ananocrystalline diamond mask layer 208 formed on the plurality of devicelayers 204, 206.

In one or more embodiments, the substrate 102, 202 can be anysemiconducting substrate known in the art, such as monocrystallinesilicon, IV-IV compounds such as silicon-germanium (Si—Ge) orsilicon-germanium-carbon (Si—Ge—C), III-V compounds, II-VI compounds,epitaxial layers over such substrates, or any other semiconducting ornon-semiconducting material, such as silicon oxide, glass, plastic,metal or ceramic substrate. In one or more embodiments, the substrate102, 202 may include integrated circuits fabricated thereon, such asdriver circuits for a memory device (not shown).

In one or more embodiments, the plurality of device layers 104, 106,204, 206 can be formed over the surface of the substrate 102, 202. Theplurality of device layers 104,106, 204, 206 can be deposited layerswhich form components of a 3D vertical NAND structure. Components may beformed by all or part of the plurality of device layers (e.g.,dielectrics, or discrete charge storage segments). The dielectricportions may be independently selected from any one or more same ordifferent electrically insulating materials, such as silicon oxide,silicon nitride, silicon oxynitride, or other high-k insulatingmaterials. In one embodiment, the structure can comprise siliconoxide/silicon nitride pairs deposited in an alternating fashion. Thepairs can be between 100 and 600 Å in total height. The number of pairscan be greater than 10 pairs, such as 32 pairs, 64 pairs or greater.

In one or more embodiments, the nanocrystalline diamond layer 108, 208is a crystalline carbon layer with a high sp³ content and a smallcrystal size. The most common chemical bonds in amorphous andnanocrystalline carbon are threefold (sp² bonding) and fourfold (sp³)bonding coordination. In the sp³ configuration, a carbon atom forms foursp³ orbitals making a strong sigma bond to the adjacent atom. In carbonfilms with high sp³ content, the sp³ content is greater than 80%, suchas greater than about 90% or greater than about 95%. The nanocrystallinediamond layer 108, 208 has a high sp³ content (e.g., nanocrystallinediamond grains) and is supported by an sp² matrix (e.g., graphite). Asused herein, small crystal size is a crystal size of less than 6 nm,such as between 2 nm and 5 nm.

In one or more embodiments, the nanocrystalline diamond layer 108produced by the first recipe has a surface roughness with a root meansquare of height deviation of greater than 25 nm. In one or moreembodiments, the first recipe may comprise a gas flow of methane(CH₄)/carbon dioxide (CO₂)/hydrogen (H₂) in a range of flow rate makingthe total flow of 100%. The nanocrystalline diamond film is depositedusing a range of microwave power of 2 to 12 kW, a pressure of 0.1 to 1Torr, and a temperature of 500° C. to 650° C.

In one or more embodiments, the nanocrystalline diamond layer 208produced by the second recipe has a surface roughness with a root meansquare of height deviation of less than about 15 nm. In one or moreembodiments, the second recipe may comprise a gas flow of methane(CH₄)/carbon dioxide (CO₂)/hydrogen (H₂)/argon (Ar) in a range of flowrate making total flow of 100%. The nanocrystalline diamond film isdeposited using a range of microwave power of 2 to 12 kW, pulsed at10-90%, a pressure of 0.1 to 1 Torr, and a temperature of 500° C. to650° C.

In one or more embodiments, the nanocrystalline diamond layer 108, 208has a density of between 2.5 g/cm³ and 3.5 g/cm³, such as a density of 3g/cm³. In one or more embodiments, the nanocrystalline diamond layer108, 208 has a stress of between −50 MPa and −150 MPa, such as a stressof between −80 MPa and −120 MPa. The nanocrystalline diamond layer 108,208 has a blanket etch selectivity of between 2 and 4.

In some embodiments, an anti-reflective coating 110, 210 is on thenanocrystalline diamond layer 108, 208, and a photoresist 112, 212 is onthe anti-reflective coating 110, 210. In some embodiments, theanti-reflective coating 110, 210 is a dielectric anti-reflective coating(DARC). Referring to FIG. 1B and FIG. 2B, the anti-reflective coating110, 210 is patterned for form openings 113, 213 that expose portions ofa top surface of the nanocrystalline diamond layer 108, 208.

With reference to FIGS. 1C and 1D and FIGS. 2C and 2D, the device 100,200 comprises a channel 114, 214. The channel 114, 214 is formed throughthe nanocrystalline diamond layer 108, 208 and the plurality of devicelayers 104, 106, 204, and 206. The channel 114, 214 can be substantiallyperpendicular to a top surface of the substrate 102, 202. For example,the channel 114, 214 may have a pillar shape. The channel 114, 214 canextend substantially perpendicularly to the top surface of the substrate102, 202. In some embodiments, the channel 114, 214 may be a filledfeature. In some other embodiments, the channel 114, 214 may be hollow.In such embodiments, an insulating fill material (not illustrated) maybe formed to fill the hollow part surrounded by the channel 114, 214.The insulating fill material may comprise any electrically insulatingmaterial, such as silicon oxide, silicon nitride, silicon oxynitride, orother high-k insulating materials.

Referring to FIG. 1D and FIG. 2D, in one or more embodiments, after thechannel 114, 214 is formed, the anti-reflective coating 110, 210 may beremoved.

Any suitable semiconductor materials can be used for the channel 114,214, for example silicon, germanium, silicon germanium, or othercompound semiconductor materials, such as III-V, II-VI, or conductive orsemi-conductive oxides, or other materials. The semiconductor materialmay be amorphous, polycrystalline or single crystal. The semiconductorchannel material may be formed by any suitable deposition methods. Forexample, in one embodiment, the semiconductor channel material isdeposited by low pressure chemical vapor deposition (LPCVD). In otherembodiments, the semiconductor channel material may be a recrystallizedpolycrystalline semiconductor material formed by recrystallizing aninitially deposited amorphous semiconductor material.

In one or more embodiments, the nanocrystalline diamond layer 108produced according to the first recipe has a thickness, T₁. In one ormore embodiments, the nanocrystalline diamond layer 108 has a thickness,T₁, in the range of about 500 Å to about 10,000 Å. Depending on the etchchemistry of the energy sensitive resist material 112 used in thefabrication sequence, an optional capping layer (not shown) may beformed on nanocrystalline diamond layer 108 prior to the formation ofenergy sensitive resist material 112. The optional capping layerfunctions as a mask for the nanocrystalline diamond layer 108 when thepattern is transferred therein and protects nanocrystalline diamondlayer 108 from energy sensitive resist material 112.

In one or more embodiments, the nanocrystalline diamond layer 208produced according to the second recipe has a thickness, T₂. In one ormore embodiments, the nanocrystalline diamond layer 208 has a thickness,T₂, in the range of about 100 Å to about 500 Å.

As depicted in FIG. 1A and FIG. 2A, energy sensitive resist material112, 212 may be formed on nanocrystalline diamond layer 108, 208. Thelayer of energy sensitive resist material 112, 212 can be spin-coated onthe substrate to a thickness within the range of about 2000 Å to about6000 Å. Most energy sensitive resist materials are sensitive toultraviolet (UV) radiation having a wavelength less than about 450 nm,and for some applications having wavelengths of 245 nm or 193 nm. Apattern is introduced into the layer of energy sensitive resist material112, 212. After energy sensitive resist material 112, 212 has beendeveloped, the desired pattern, consisting of apertures/openings 111,211, is present in energy sensitive resist material 112, 212, as shownin FIG. 1A and FIG. 2A. Thereafter, referring to FIG. 1B and FIG. 2B,the pattern defined in energy sensitive resist material 112, 212 istransferred through the anti-reflective coating 110, 210 using theenergy sensitive resist material 110, 210 as a mask and formingopenings/apertures 113, 213.

Referring to FIG. 1C and FIG. 2C, the pattern defined in anti-reflectivecoating 110, 210 is transferred through the nanocrystalline diamondlayer 108, 208. An appropriate chemical etchant is used that selectivelyetches nanocrystalline diamond layer 108, 208 over the energy sensitiveresist material 110, 210 and the plurality of material layers 104, 106,204, 206 extending apertures 113, 213 to the substrate 102, 202 formingchannel 114, 214. Appropriate chemical etchants include ozone, oxygen,or ammonia plasmas.

Current carbon hard mask films are deposited at very high temperaturesand have low hydrogen (H) content, but the films are largely sp²,resulting in lower density and modulus, leading to lower etchselectivity and pattern integrity. Modulus is a measurement of themechanical strength of the film. Films, particularly thick films, withlow modulus have line wiggling and other issues.

FIGS. 3A-3C illustrate cross-sectional views of a device 300 beingprocessed according to method of one or more embodiments. FIG. 5illustrates a process flow diagram of a method 500 according to one ormore embodiments. In some embodiments, a substrate is provided forprocessing prior to operation 502. As used in this regard, the term“provided” means that the substrate is placed into a position orenvironment for further processing. In one or more embodiments, thesubstrate is maintained at a temperature in a range of from about 200°C. to about 1000° C., including a range of from about 500° C. to about650° C.

In one or more embodiments, the process chamber used can be any CVDprocess chamber with a plasma source (e.g. remote, microwave,capacitively coupled plasma (CCP), or inductively coupled plasma (ICP)),such as one of the process chambers described above. In someembodiments, flow rates and other processing parameters described beloware for a 300 mm substrate. It should be understood these parameters canbe adjusted based on the size of the substrate processed and the type ofchamber used without diverging from the embodiments disclosed herein.

A “substrate surface”, as used herein, refers to any substrate ormaterial surface formed on a substrate upon which film processing can beperformed. For example, a substrate surface on which processing can beperformed includes materials such as silicon, silicon oxide, siliconnitride, doped silicon, germanium, gallium arsenide, gallium nitride,glass, sapphire, and any other materials such as metals, metal nitrides,metal alloys, and other conductive materials, depending on theapplication. A substrate surface may also include dielectric materialssuch as silicon dioxide and carbon doped silicon oxides. Substrates mayhave various dimensions, such as 200 mm, 300 mm, or other diameterwafers, as well as rectangular or square panes.

A device layer can then be deposited on the processing surface. Thedevice layer can be a device layer as described with reference to FIGS.1A-1D and FIGS. 2A-2D. Further, the device layer can be one of aplurality of device layers. The device layers can act in conjunction toform one or more features or components, such as components of a 3D NANDdevice.

At operation 502, a first nanocrystalline diamond layer is deposited onthe substrate, or, in some embodiments, on the device layer. The firstnanocrystalline diamond layer can have an average grain size of lessthan 6 nm. In one example, the first nanocrystalline diamond layer hasan average grain size of between 2 nm and 5 nm. A small grain size, suchas below 6 nm, allows for better control of adhesion between the hardmask layer, such as the nanocrystalline diamond layer, and theunderlying layer and smaller size for the hard mask layer. The randompositioning of a larger grain size during deposition will increase thenumber of non-contact spaces between the hard mask layer and theunderlying layer. The non-contact space is the space between the hardmask layer and the underlying layer where the hard mask layer is not indirect contact with the underlying layer due to shape and size of thegrains of the hard mask layer and due to the roughness of the underlyinglayer itself. A larger non-contact space decrease the adhesion of thelayer and decreases the thermal transfer between the hard mask and theunderlying layer. The size of non-contact space is reduced by smallergrains, because smaller grains, when deposited as part of a layer, canbe more tightly packed than larger grains. Further, due to the smallergrain size, the layer can be made thinner than larger grain size layerswhile maintaining good contact with the underlying layer.

The deposition of the first nanocrystalline diamond layer at operation502 can begin by delivering a deposition gas to a CVD process chamberwith a plasma source (e.g. remote, microwave, CCP, or ICP) at a firstpressure. The deposition gas includes a carbon-containing precursor anda hydrogen containing gas. In one or more embodiments, thecarbon-containing precursor is an alkane precursor. The alkane precursorcan be a saturated unbranched hydrocarbon, such as methane, ethane,propane, and combinations thereof. Other alkane precursors includen-butane, n-pentane, n-hexane, n-heptane, n-octane, and combinationsthereof. The hydrogen containing gas can include hydrogen (H₂), water(H₂O), ammonia (NH₃) or other hydrogen containing molecules.

The deposition gas is then delivered to the CVD process chamber. Thedeposition gas can either mix within the chamber or be mixed prior toentering the chamber. The deposition gas is delivered at a relativelyhigh pressure, such as greater than 5 Torr. In one embodiment, thedeposition gas is delivered at between about 10 Torr and 100 Torr, suchas about 50 Torr.

The deposition gas can then be activated to create an activateddeposition gas. The deposition gas can be activated by forming a plasmausing a power source. Any power source capable of activating the gasesinto reactive species and maintaining the plasma of reactive species maybe used. For example, radio frequency (RF), direct current (DC), ormicrowave (MW) based power discharge techniques may be used. The powersource produces a source plasma power which is applied to the CVDprocess chamber with a plasma source (e.g. remote, microwave, CCP, orICP) to generate and maintain a plasma of the deposition gas. Inembodiments which use an RF power for the source plasma power, thesource plasma power can be delivered at a frequency of from about 2 MHzto about 170 MHz and at a power level of between 500 W and 12,000 W.Other embodiments include delivering the source plasma power at fromabout 2000 W to about 12,000 W. The power applied can be adjustedaccording to size of the substrate being processed. In one or moreembodiments, the microwave plasma is applied as a continuous wave at apower in a range of about 2 to about 12 kilo watts (kW).

Based on the high pressure in the CVD chamber, as well as other factors,ionized species formation will be minimized while radical formation ismaximized. Without intending to be bound by theory, it is believed thatthe nanocrystalline diamond layer should be primarily sp³ bonds ratherthan sp² bonds. Further, it is believed that more sp³ bonding can beachieved by increasing the number of radical species over ionizedspecies during the deposition of the layer. Ionized species are highlyenergetic can need more room for movement than radicals. By increasingthe pressure, electron energy is reduced while the likelihood ofcollision with other molecules increases. The decrease in electronenergy and increase in number of collisions favors radical formationover ion formation.

Once activated, the activated deposition gas is then delivered through asecond volume having a second pressure. The second volume can be asecond chamber or another confined area between the process volume andthe CVD chamber with a plasma source. In one example, the second volumeis the connection between the CVD chamber with a plasma source and theprocess volume.

The second pressure is less than the first pressure. The movement fromthe remote plasma chamber to the second volume either based on flowrate, change in overall volume or combinations thereof results in areduced pressure of the activated deposition gas in the second volume.The pressure is reduced to allow for better deposition from the radicalspecies while reducing ionized species collision with the depositedlayer. In one embodiment, the second pressure is between about 0.1 Torrand about 5 Torr. In one or more embodiments, the second pressure is ina range of about 0.1 Torr to about 1 Torr.

In one or more embodiments, the activated deposition gas comprisingmethane (CH₄)/carbon dioxide (CO₂) at a range of flow rate of about 2sccm to about 10 sccm is then delivered to a substrate in a processvolume of a process chamber. The substrate can be of any composition,such as a crystalline silicon substrate. The substrate can also includeone or more features, such as a via or an interconnect. The substratecan be supported on a substrate support. The substrate support can bemaintained in a specific temperature range. In one embodiment, thesubstrate support is maintained in a temperature range of between about500° C. and about 650° C.

As illustrated in FIG. 3A, the substrate 302 can be preseeded fordeposition of the nanocrystalline layer. In one embodiment, thesubstrate 302 is immersed or otherwise coated in a seeding solution toform suspended nanodiamonds 304 on the substrate 302. The seedingsolution may be an ethanol based nanodiamond suspension. The substrate302 may be immersed in the suspension during an ultrasonic treatment,which adheres some of the suspended nanodiamonds 304 to the surface ofthe substrate 302. Other preseeding techniques can be employed withoutdiverging from the embodiments described herein.

Referring to FIG. 3B, a first nanocrystalline diamond layer 306 is thendeposited on a surface of the substrate 302. The radicals from thepreviously formed activated deposition gas impinge on the substratesurface to form the first nanocrystalline diamond layer 306. Lowpressure is believed to be beneficial to the formation of sp³ bonding inthe first nanocrystalline diamond layer 306 from the remotely formedradicals. The higher pressure in the CVD plasma chamber allows forpreferential radical formation while the lower pressure in the processvolume allows for more uniform deposition from the previously formedradicals.

Once the first nanocrystalline diamond layer 306 is deposited, ahydrogen containing gas is delivered to the CVD plasma chamber. Thehydrogen containing gas can be delivered at a separate time or the gasflow from the previous step can be maintained. No alkane precursor ispresent for this portion. The hydrogen containing gas can be deliveredwith an inert gas or as part of a combination of multiple hydrogencontaining gases. In one or more embodiments, the hydrogen (H₂) gas isdelivered with a range of flow rate of about 90 sccm to about 96 sccm.

The hydrogen containing gas is then activated to create an activatedhydrogen containing gas. The hydrogen containing gas can be converted toa plasma using the same pressure, temperature, power type, power rangesand other parameters for formation of the plasma discussed withreference to forming the activated deposition gas.

Once the activated hydrogen containing gas is formed, it can bedelivered to the substrate in the process volume. The process volume andthe substrate may be maintained at the same pressure, temperature andother parameters as described above. During the deposition process, itis believed that polymers can form on the surface of the depositednanocrystalline diamond layer. The polymers can affect furtherdeposition and otherwise degrade performance of the deposited layer. Bydelivering the activated hydrogen containing gas to the deposited layer,the polymers are made volatile and can then be removed from the chamber,such that they do not affect subsequent deposition processes.

The above elements can then be repeated to deposit a secondnanocrystalline diamond layer 308 with a lower roughness than the firstnanocrystalline diamond layer 306. At operation 504 a secondnanocrystalline diamond layer 308 is deposited on the firstnanocrystalline diamond layer. The second nanocrystalline diamond layercan have an average grain size of less than 6 nm. In one example, thesecond nanocrystalline diamond layer has an average grain size ofbetween 2 nm and 5 nm. A small grain size, such as below 6 nm, allowsfor better control of adhesion between the hard mask layer, such as thesecond nanocrystalline diamond layer, and the underlying layer andsmaller size for the hard mask layer. The random positioning of a largergrain size during deposition will increase the number of non-contactspaces between the hard mask layer and the underlying layer. Thenon-contact space is the space between the hard mask layer and theunderlying layer where the hard mask layer is not in direct contact withthe underlying layer due to shape and size of the grains of the hardmask layer and due to the roughness of the underlying layer itself. Alarger non-contact space decrease the adhesion of the layer anddecreases the thermal transfer between the hard mask and the underlyinglayer. The size of non-contact space is reduced by smaller grains,because smaller grains, when deposited as part of a layer, can be moretightly packed than larger grains. Further, due to the smaller grainsize, the layer can be made thinner than larger grain size layers whilemaintaining good contact with the underlying layer.

The deposition of the second nanocrystalline diamond layer at operation504 can begin by delivering a deposition gas to a CVD plasma chamber ata first pressure. The deposition gas includes a carbon-containingprecursor and a hydrogen containing gas. In one or more embodiments, thecarbon-containing precursor is an alkane precursor. The alkane precursorcan be a saturated unbranched hydrocarbon, such as methane, ethane,propane, and combinations thereof. Other alkane precursors includen-butane, n-pentane, n-hexane, n-heptane, n-octane, and combinationsthereof. The hydrogen containing gas can include hydrogen (H₂), water(H₂O), ammonia (NH₃) or other hydrogen containing molecules. Thedeposition gas can further include an inert gas. The inert gas can be anoble gas, such as argon (Ar).

The deposition gas is then delivered to the CVD plasma chamber. Thedeposition gas can either mix within the chamber or be mixed prior toentering the chamber. The deposition gas is delivered at a relativelyhigh pressure, such as greater than 5 Torr. In one embodiment, thedeposition gas is delivered at between about 10 Torr and 100 Torr, suchas about 50 Torr.

The deposition gas can then be activated to create an activateddeposition gas. The deposition gas can be activated by forming a plasmausing a power source. Any power source capable of activating the gasesinto reactive species and maintaining the plasma of reactive species maybe used. For example, radio frequency (RF), direct current (DC), ormicrowave (MW) based power discharge techniques may be used. The powersource produces a source plasma power which is applied to the CVD plasmachamber to generate and maintain a plasma of the deposition gas. Inembodiments which use an RF power for the source plasma power, thesource plasma power can be delivered at a frequency of from about 2 MHzto about 170 MHz and at a power level of between 500 W and 12,000 W.Other embodiments include delivering the source plasma power at fromabout 2000 W to about 12,000 W. The power applied can be adjustedaccording to size of the substrate being processed.

Based on the high pressure in the remote plasma chamber, as well asother factors, ionized species formation will be minimized while radicalformation is maximized. Without intending to be bound by theory, it isbelieved that the nanocrystalline diamond layer should be primarily sp³bonds rather than sp² bonds. Further, it is believed that more sp³bonding can be achieved by increasing the number of radical species overionized species during the deposition of the layer. Ionized species arehighly energetic can need more room for movement than radicals. Byincreasing the pressure, electron energy is reduced while the likelihoodof collision with other molecules increases. The decrease in electronenergy and increase in number of collisions favors radical formationover ion formation.

Once activated, the activated deposition gas comprising methane(CH₄)/carbon dioxide (CO₂)/argon (Ar) at a range of flow rate of2-10/2-10/2-90 sccm is then delivered through a second volume having asecond pressure. The second volume can be a second chamber or anotherconfined area between the process volume and the CVD plasma chamber. Inone example, the second volume is the connection between the CVD plasmachamber and the process volume.

The second pressure is less than the first pressure. The movement fromthe CVD plasma chamber to the second volume either based on flow rate,change in overall volume or combinations thereof results in a reducedpressure of the activated deposition gas in the second volume. Thepressure is reduced to allow for better deposition from the radicalspecies while reducing ionized species collision with the depositedlayer. In one embodiment, the second pressure is between about 0.1 Torrand about 5 Torr. In one or more embodiments, the second pressure is ina range of from about 0.1 Torr to about 1 Torr.

The activated deposition gas, a mixture of methane (CH₄)/carbon dioxide(CO₂)/argon (Ar) is then delivered to a substrate in a process volume ofa process chamber with a range of flow rate of about 2-10/2-10/2-90sccm, respectively. In one embodiment, the substrate support ismaintained in a temperature range of between about 500° C. and about650° C.

A second nanocrystalline diamond layer 308 is then deposited on asurface of the first nanocrystalline diamond layer 306. The radicalsfrom the previously formed activated deposition gas impinge on thesurface to form the second nanocrystalline diamond layer 308. Lowpressure is believed to be beneficial to the formation of sp³ bonding inthe second nanocrystalline diamond layer 308 from the remotely formedradicals. The higher pressure in the remote plasma source allows forpreferential radical formation while the lower pressure in the processvolume allows for more uniform deposition from the previously formedradicals. The second nanocrystalline diamond layer 308 has a smoothsurface with a roughness (AFM) of less than about 15 nm.

Once the nanocrystalline diamond layer is deposited, a hydrogencontaining gas is delivered to the remote plasma chamber. The hydrogencontaining gas can be delivered at a separate time or the gas flow fromthe previous step can be maintained. No alkane precursor is present forthis portion. The hydrogen containing gas can be delivered with an inertgas or as part of a combination of multiple hydrogen containing gases.In one or more embodiments, the hydrogen (H₂) gas is delivered with aflow rate of from about 1 sccm to about 94 sccm, including a range offrom about 15 sccm to about 45 sccm.

The hydrogen containing gas is then activated to create an activatedhydrogen containing gas. The hydrogen containing gas can be converted toa plasma using the same pressure, temperature, power type, power rangesand other parameters for formation of the plasma discussed withreference to forming the activated deposition gas.

Once the activated hydrogen containing gas is formed, it can bedelivered to the substrate in the process volume. The process volume andthe substrate may be maintained at the same pressure, temperature andother parameters as described above. During the deposition process, itis believed that polymers can form on the surface of the depositednanocrystalline diamond layer. The polymers can affect furtherdeposition and otherwise degrade performance of the deposited layer. Bydelivering the activated hydrogen containing gas to the deposited layer,the polymers are made volatile and can then be removed from the chamber,such that they do not affect subsequent deposition processes.

At decision point 506, it is determined whether the nanocrystalline hardmask 308 has achieved a predetermined roughness and thickness. Eachdeposition cycle produces a thickness of between about 20 Å and about200 Å, such as about 100 Å. By repeating the above steps, the previouslayer acts as a seed layer for the next deposition, allowing for anoverall desired thickness to be deposited. In one embodiment, thenanocrystalline diamond stack is deposited to 1 μm thick.

If, at decision point 506, the nanocrystalline diamond stack is toorough or not thick enough, the cycle returns to operation 502 and 504for further deposition steps.

If, at decision point 506, the nanocrystalline diamond stack hasobtained the desired roughness and thickness, processing continues. Atoperation 508, the nanocrystalline diamond layer can, optionally, thenbe patterned and etched. Patterning can include deposition of aphotoresist 112, 212 over the nanocrystalline diamond layer. Thephotoresist 112, 212 is then exposed to an appropriate wavelength ofradiation to create a pattern of openings/apertures 111, 211. Thepattern is then etched into both the photoresist 112, 212, and then thenanocrystalline diamond layer.

At operation 510, the device can then be etched to form a feature orchannel. With the pattern formed in the nanocrystalline diamond layer,the device can then be etched. The device is etched by an etchant whichis selective for the device layer 104, 106, 204, 206 over thenanocrystalline diamond layer 108, 208. The device layer is etched usingchemistry and techniques well known in the art. In one embodiment, theetchant is a chlorine containing etchant.

At operation 512, the nanocrystalline diamond layer can then be removedfrom the surface of the device. The nanocrystalline diamond layer can beashed, for example, from the surface of the device layer using a plasmaash process. The plasma ash process can include activating anoxygen-containing gas, such as O₂. When using O₂, the ash rate is about900 Å/min or greater. The nanocrystalline diamond layer may be ashedusing a high aspect ratio etch system.

FIGS. 4A-4D illustrate cross-sectional views of a device 400 beingprocessed according to method of one or more embodiments. FIG. 6illustrates a process flow diagram of a method 600 according to one ormore embodiments. In some embodiments, a substrate is provided forprocessing prior to operation 602. As used in this regard, the term“provided” means that the substrate is placed into a position orenvironment for further processing. In one or more embodiments, thesubstrate is maintained at a temperature in a range of from about 500°C. to about 650° C.

A device layer can then be deposited on the processing surface. Thedevice layer can be a device layer as described with reference to FIGS.1A-1D and FIGS. 2A-2D. Further, the device layer can be one of aplurality of device layers. The device layers can act in conjunction toform one or more features or components, such as components of a 3D NANDdevice.

At operation 602, a nanocrystalline diamond layer is deposited on thesubstrate, or, in some embodiments, on the device layer. Thenanocrystalline diamond layer can have an average grain size of lessthan 6 nm. In one example, the nanocrystalline diamond layer has anaverage grain size of between 2 nm and 5 nm. A small grain size, such asbelow 6 nm, allows for better control of adhesion between the hard masklayer, such as the nanocrystalline diamond layer, and the underlyinglayer and smaller size for the hard mask layer. The random positioningof a larger grain size during deposition will increase the number ofnon-contact spaces between the hard mask layer and the underlying layer.The non-contact space is the space between the hard mask layer and theunderlying layer where the hard mask layer is not in direct contact withthe underlying layer due to shape and size of the grains of the hardmask layer and due to the roughness of the underlying layer itself. Alarger non-contact space decrease the adhesion of the layer anddecreases the thermal transfer between the hard mask and the underlyinglayer. The size of non-contact space is reduced by smaller grains,because smaller grains, when deposited as part of a layer, can be moretightly packed than larger grains. Further, due to the smaller grainsize, the layer can be made thinner than larger grain size layers whilemaintaining good contact with the underlying layer.

The deposition of the nanocrystalline diamond layer at operation 602 canbegin by delivering a deposition gas to a CVD chamber (with a plasmasource) at a first pressure. The deposition gas includes acarbon-containing precursor and a hydrogen containing gas. In one ormore embodiments, the carbon-containing precursor is an alkaneprecursor. The alkane precursor can be a saturated unbranchedhydrocarbon, such as methane, ethane, propane, and combinations thereof.Other alkane precursors include n-butane, n-pentane, n-hexane,n-heptane, n-octane, and combinations thereof. The hydrogen containinggas can include hydrogen (H₂), water (H₂O), ammonia (NH₃) or otherhydrogen containing molecules.

The deposition gas is then delivered to the CVD chamber (with a plasmasource). The deposition gas can either mix within the chamber or bemixed prior to entering the chamber. The deposition gas is delivered ata relatively high pressure, such as greater than 5 Torr. In oneembodiment, the deposition gas is delivered at between about 10 Torr and100 Torr, such as about 50 Torr.

The deposition gas can then be activated to create an activateddeposition gas. The deposition gas can be activated by forming a plasmausing a power source. Any power source capable of activating the gasesinto reactive species and maintaining the plasma of reactive species maybe used. For example, radio frequency (RF), direct current (DC), ormicrowave (MW) based power discharge techniques may be used. The powersource produces a source plasma power which is applied to the CVDchamber (with a plasma source) to generate and maintain a plasma of thedeposition gas. In embodiments which use an RF power for the sourceplasma power, the source plasma power can be delivered at a frequency offrom about 2 MHz to about 170 MHz and at a power level of between 500 Wand 12,000 W. Other embodiments include delivering the source plasmapower at from about 2000 W to about 12,000 W. The power applied can beadjusted according to size of the substrate being processed. In one ormore embodiments, the microwave plasma is applied as a continuous waveat a range of power of from about 2 kilo watts (kW) to about 12 kilowatts (kW).

Based on the high pressure in the CVD chamber (with a plasma source), aswell as other factors, ionized species formation will be minimized whileradical formation is maximized. Without intending to be bound by theory,it is believed that the nanocrystalline diamond layer should beprimarily sp³ bonds rather than sp² bonds. Further, it is believed thatmore sp³ bonding can be achieved by increasing the number of radicalspecies over ionized species during the deposition of the layer. Ionizedspecies are highly energetic can need more room for movement thanradicals. By increasing the pressure, electron energy is reduced whilethe likelihood of collision with other molecules increases. The decreasein electron energy and increase in number of collisions favors radicalformation over ion formation.

Once activated, the activated deposition gas is then delivered through asecond volume having a second pressure. The second volume can be asecond chamber or another confined area between the process volume andthe remote plasma chamber. In one example, the second volume is theconnection between the remote plasma chamber and the process volume.

The second pressure is less than the first pressure. The movement fromthe remote plasma chamber to the second volume either based on flowrate, change in overall volume or combinations thereof results in areduced pressure of the activated deposition gas in the second volume.The pressure is reduced to allow for better deposition from the radicalspecies while reducing ionized species collision with the depositedlayer. In one embodiment, the second pressure is between about 0.1 Torrand about 5 Torr. In one or more embodiments, the second pressure is ina range of from about 0.1 Torr to about 1 Torr.

The activated deposition gas comprising methane (CH₄)/carbon dioxide(CO₂) at a range of flow rate of 2 sccm to 10 sccm is then delivered toa substrate in a process volume of a process chamber. The substrate canbe of any composition, such as a crystalline silicon substrate. Thesubstrate can also include one or more features, such as a via or aninterconnect. The substrate can be supported on a substrate support. Thesubstrate support can be maintained in a specific temperature range. Inone embodiment, the substrate support is maintained in a temperaturerange of between about 500° C. and about 650° C.

As illustrated in FIG. 4A, the substrate 402 can be preseeded fordeposition of the nanocrystalline layer. In one embodiment, thesubstrate 402 is immersed or otherwise coated in a seeding solution toform suspended nanodiamonds 404 on the substrate 402. The seedingsolution may be an ethanol based nanodiamond suspension. The substrate402 may be immersed in the suspension during an ultrasonic treatment,which adheres some of the suspended nanodiamonds 404 to the surface ofthe substrate 402. Other preseeding techniques can be employed withoutdiverging from the embodiments described herein.

Referring to FIG. 4B, a nanocrystalline diamond layer 406 is thendeposited on a surface of the substrate 402. The radicals from thepreviously formed activated deposition gas impinge on the substratesurface to form the nanocrystalline diamond layer 406. Low pressure isbelieved to be beneficial to the formation of sp³ bonding in thenanocrystalline diamond layer 406 from the remotely formed radicals. Thehigher pressure in the remote plasma source allows for preferentialradical formation while the lower pressure in the process volume allowsfor more uniform deposition from the previously formed radicals.

Once the nanocrystalline diamond layer 406 is deposited, a hydrogencontaining gas is delivered to the CVD chamber (with a plasma source).The hydrogen containing gas can be delivered at a separate time or thegas flow from the previous step can be maintained. No alkane precursoris present for this portion. The hydrogen containing gas can bedelivered with an inert gas or as part of a combination of multiplehydrogen containing gases. In one or more embodiments, the hydrogen (H₂)gas is delivered with a range of flow rate of 90 sccm to 96 sccm.

The hydrogen containing gas is then activated to create an activatedhydrogen containing gas. The hydrogen containing gas can be converted toa plasma using the same pressure, temperature, power type, power rangesand other parameters for formation of the plasma discussed withreference to forming the activated deposition gas.

Once the activated hydrogen containing gas is formed, it can bedelivered to the substrate in the process volume. The process volume andthe substrate may be maintained at the same pressure, temperature andother parameters as described above. During the deposition process, itis believed that polymers can form on the surface of the depositednanocrystalline diamond layer. The polymers can affect furtherdeposition and otherwise degrade performance of the deposited layer. Bydelivering the activated hydrogen containing gas to the deposited layer,the polymers are made volatile and can then be removed from the chamber,such that they do not affect subsequent deposition processes.

With reference to FIG. 4C and FIG. 6, at operation 604, thenanocrystalline diamond layer 406 is exposed to an inert gas plasma toform a smooth surface nanocrystalline diamond layer 408. In one or moreembodiments, the gas flow comprises an inert gas selected from one ormore of helium (He), neon (Ne), and argon (Ar). In one or more specificembodiments, the inert gas plasma comprises argon (Ar), delivered with arange of flow rate of about 50 sccm to about 200 sccm, pulsed withmicrowave power in a range of from about 2 kW to about 12 kW at 10-90%,a pressure in a range of from about 0.1 Torr to about 1 Torr, and at atemperature in a range of from about 500° C. to about 650° C.

The inert gas is then delivered to the remote plasma chamber. The inertgas is delivered at a relatively high pressure, such as greater than 5Torr. In one embodiment, the inert gas is delivered at between about 10Torr and 100 Torr, such as about 50 Torr.

The inert gas can then be activated to create an activated inert gas.The inert gas can be activated by forming a plasma using a power source.Any power source capable of activating the gases into reactive speciesand maintaining the plasma of reactive species may be used. For example,radio frequency (RF), direct current (DC), or microwave (MW) based powerdischarge techniques may be used. The power source produces a sourceplasma power which is applied to the CVD chamber (with a plasma source)to generate and maintain a plasma of the inert gas. In embodiments whichuse an RF power for the source plasma power, the source plasma power canbe delivered at a frequency of from about 2 MHz to about 170 MHz and ata power level of between 500 W and 12,000 W. Other embodiments includedelivering the source plasma power at from about 2000 W to about 12,000W. The power applied can be adjusted according to size of the substratebeing processed.

Based on the high pressure in the CVD chamber (with a plasma source), aswell as other factors, ionized species formation will be minimized whileradical formation is maximized, leading to a smoothing of the surface ofthe nanocrystalline diamond layer 406 surface to form a smoothenednanocrystalline diamond layer 408.

Once activated, the activated inert gas comprising argon (Ar) at a rangeof flow rate of about 50 sccm to about 200 sccm is then deliveredthrough a second volume having a second pressure. The second volume canbe a second chamber or another confined area between the process volumeand the remote plasma chamber. In one example, the second volume is theconnection between the remote plasma chamber and the process volume.

The second pressure is less than the first pressure. The movement fromthe remote plasma chamber to the second volume either based on flowrate, change in overall volume or combinations thereof results in areduced pressure of the activated deposition gas in the second volume.The pressure is reduced to allow for better deposition from the radicalspecies while reducing ionized species collision with the depositedlayer. In one embodiment, the second pressure is between about 0.1 Torrand about 5 Torr. In one or more embodiments, the second pressure is ina range of from about 0.1 Torr to about 1 Torr.

The activated inert gas is then delivered to the nanocrystalline diamondlayer 406 in a process volume of a process chamber with a range of flowrate of about 50 sccm to about 200 sccm. In one embodiment, thesubstrate support is maintained in a temperature range of between about500° C. and about 650° C.

The smooth nanocrystalline diamond layer 408 has a smooth surface with aroughness (AFM) of less than about 15 nm.

At decision point 606, it is determined whether the smoothnanocrystalline hard mask 408 has achieved a predetermined roughness andthickness. Each deposition cycle produces a thickness of between about20 Å and about 200 Å, such as about 100 Å. By repeating the above steps,the previous layer acts as a seed layer for the next deposition,allowing for an overall desired thickness to be deposited. In oneembodiment, the nanocrystalline diamond stack is deposited to 1 μmthick.

If, at decision point 606, the nanocrystalline diamond stack is toorough or not thick enough, the cycle returns to operation 602 and 604for further deposition and smoothing steps to result in a thick andsmooth nanocrystalline diamond stack 410 (see FIG. 4D).

If, at decision point 606, the nanocrystalline diamond stack hasobtained the desired roughness and thickness, processing continues. Atoperation 608, the nanocrystalline diamond layer can, optionally, thenbe patterned and etched. Patterning can include deposition of aphotoresist 112, 212 over the nanocrystalline diamond layer. Thephotoresist 112, 212 is then exposed to an appropriate wavelength ofradiation to create a pattern of openings/apertures 111, 211. Thepattern is then etched into both the photoresist 112, 212, and then thenanocrystalline diamond layer.

At operation 610, the device can then be etched to form a feature orchannel. With the pattern formed in the nanocrystalline diamond layer,the device can then be etched. The device is etched by an etchant whichis selective for the device layer 104, 106, 204, 206 over thenanocrystalline diamond layer 108, 208. The device layer is etched usingchemistry and techniques well known in the art. In one embodiment, theetchant is a chlorine containing etchant.

At operation 612, the nanocrystalline diamond layer can then be removedfrom the surface of the device. The nanocrystalline diamond layer can beashed, for example, from the surface of the device layer using a plasmaash process. The plasma ash process can include activating anoxygen-containing gas, such as O₂. When using O₂, the ash rate is about900 Å/min or greater. The nanocrystalline diamond layer may be ashedusing a high aspect ratio etch system.

In the foregoing specification, embodiments of the disclosure have beendescribed with reference to specific exemplary embodiments thereof. Itwill be evident that various modifications may be made thereto withoutdeparting from the broader spirit and scope of the embodiments of thedisclosure as set forth in the following claims. The specification anddrawings are, accordingly, to be regarded in an illustrative senserather than a restrictive sense.

Reference throughout this specification to “one embodiment,” “certainembodiments,” “one or more embodiments” or “an embodiment” means that aparticular feature, structure, material, or characteristic described inconnection with the embodiment is included in at least one embodiment ofthe disclosure. Thus, the appearances of the phrases such as “in one ormore embodiments,” “in certain embodiments,” “in one embodiment” or “inan embodiment” in various places throughout this specification are notnecessarily referring to the same embodiment of the disclosure.Furthermore, the particular features, structures, materials, orcharacteristics may be combined in any suitable manner in one or moreembodiments.

Although the disclosure herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent disclosure. It will be apparent to those skilled in the art thatvarious modifications and variations can be made to the method andapparatus of the present disclosure without departing from the spiritand scope of the disclosure. Thus, it is intended that the presentdisclosure include modifications and variations that are within thescope of the appended claims and their equivalents.

What is claimed is:
 1. A processing method comprising: depositing afirst nanocrystalline diamond layer on a substrate, the firstnanocrystalline diamond layer having a first thickness, a firstroughness, a first hardness, and a first modulus; and depositing asecond nanocrystalline diamond layer on the first nanocrystallinediamond layer, the second nanocrystalline diamond layer having a secondthickness, and a second roughness, wherein the first thickness isgreater than the second thickness, and the second roughness is less thanthe first roughness.
 2. The processing method of claim 1, whereindepositing the first nanocrystalline diamond layer comprises generatinga deposition gas comprising a carbon-containing gas and carbon dioxideand activating the deposition gas to form a plasma.
 3. The processingmethod of claim 1, further comprising depositing a seed layer on thesubstrate prior to depositing the first nanocrystalline diamond layer.4. The processing method of claim 3, wherein the seed layer comprises ananocrystalline diamond.
 5. The processing method of claim 2, furthercomprising exposing the substrate to a hydrogen plasma to form the firstnanocrystalline diamond layer.
 6. The processing method of claim 1,wherein depositing the second nanocrystalline layer comprises generatinga deposition gas comprising a carbon-containing gas, carbon dioxide, andan inert gas and activating the deposition gas to form a plasma.
 7. Theprocessing method of claim 6, further comprising exposing the firstnanocrystalline diamond layer to a hydrogen plasma to form the secondnanocrystalline diamond layer.
 8. The processing method of claim 1,wherein the first thickness is in a range of from about 250 nm to about650 nm.
 9. The processing method of claim 1, wherein the secondthickness is in a range of from about 5 nm to about 200 nm.
 10. Theprocessing method of claim 1, wherein the first roughness is greaterthan about 25 nm.
 11. The processing method of claim 1, wherein thesecond roughness is less than about 15 nm.
 12. A processing methodcomprising: depositing a first nanocrystalline diamond layer on the seedlayer, the first nanocrystalline diamond layer having a first thickness,a first roughness, a first hardness, and a first modulus; and exposingthe first nanocrystalline diamond layer to an inert gas plasma to form asmooth nanocrystalline diamond layer.
 13. The processing method of claim12, wherein depositing the first nanocrystalline diamond layer comprisesgenerating a deposition gas comprising a carbon-containing gas andcarbon dioxide and activating the deposition gas to form a plasma. 14.The processing method of claim 12, further comprising depositing a seedlayer on the substrate prior to depositing the first nanocrystallinediamond layer.
 15. The processing method of claim 14, wherein the seedlayer comprises a nanocrystalline diamond.
 16. The processing method ofclaim 13, further comprising exposing the substrate to a hydrogen plasmato form the first nanocrystalline diamond layer.
 17. The processingmethod of claim 12, wherein the inert gas plasma comprises one or moreof helium (He), neon (Ne), and argon (Ar).
 18. The processing method ofclaim 12, wherein the first roughness is greater than about 25 nm. 19.The processing method of claim 12, wherein the smooth nanocrystallinediamond layer has a second roughness of less than about 15 nm.
 20. Amemory device comprising: a memory stack comprising a plurality ofalternating layers of a first material and a second material on asubstrate; a nanocrystalline diamond layer on the memory stack, thenanocrystalline diamond layer has a roughness of less than about 15 nm;and a memory channel extending from a top surface of the memory stack tothe substrate.